Recently, a tablet computer is introduced into the market. Due to the slim shape, the tablet computer is now rapidly gaining in popularity. Generally, the display screen of the tablet computer is a touch screen. Via the touch screen, the user may input commands into the tablet computer to control operations of the tablet computer. Generally, when the user wants to input a character or a symbol into the tablet computer, an on-screen keyboard is enabled and shown on the touch screen of the tablet computer. The on-screen keyboard is virtual keyboard simulating the real keyboard device. By touching an icon of the on-screen keyboard, a corresponding character or symbol is inputted into the tablet computer. In other words, characters or symbols may be directly inputted into the tablet computer without any external keyboard device.
As known, the area of the display screen of the tablet computer is usually smaller than the area of the general keyboard device. Consequently, the icon of the on-screen keyboard shown on the tablet computer is usually smaller than the key of the general keyboard device. Under this circumstance, the on-screen keyboard may be erroneously touched by the user. Moreover, the use of the touch screen to input characters or symbols becomes hindrance for most users who are familiar with the general personal computers or notebook computers. Consequently, in many circumstances, an external keyboard is additionally prepared by the user. For operating the tablet computer, the external keyboard is in communication with the tablet computer. In addition, the tablet computer is placed and supported on a prop stand (e.g. a bookshelf). That is, the tablet computer is considered as a display screen with a host, and the external keyboard is used for inputting characters or symbols.
For complying with the requirement of using the external keyboard device for the tablet computer, an input device with a supporting function has been disclosed. Such an input device can provide the functions of fixing the external keyboard and supporting the tablet computer. FIG. 1 is a schematic perspective view illustrating a conventional input device with a supporting function. The conventional input device 1 comprises a base 10, an upper cover 11 and a keyboard 12. A prop tray 101 is disposed within the base 10. The prop tray 101 may be pulled out from the base 10. In addition, the prop tray 101 has a plurality of stopping parts 102. The upper cover 11 has a foldable part 111. After the upper cover 11 is lifted and the keyboard 12 is exposed, the foldable part 111 may be folded backwardly and then stopped by the one of the stopping parts 102. Meanwhile, the tablet computer 13 may be placed on the base 10 and the tablet computer 13 is supported by the upper cover 11. Consequently, the viewing angle of the tablet computer 13 is suitable to the user.
However, the conventional input device still has some drawbacks. For example, the space of the base is mainly used for accommodating the prop tray and the controller (or controlling circuit) of the keyboard. The remaining space of the base is usually useless. In other words, the space utilization of the base is usually insufficient.